Mobile devices including cellular phones, personal digital aids and miniature computers are widely used as they are easily carried around and can perform many tasks. One problem of the mobile devices is text entry, which is problematic due to their small size. One solution for text entry in mobile devices is using a limited key set in which at least some of the keys are ambiguously associated with a plurality of letters. Upon receiving a sequence of key strokes, a word dictionary is consulted to guess the word intended by the user. Such a solution is described, for example, in U.S. Pat. No. 5,818,437 to Grover et al., titled: “Reduced Keyboard Disambiguating Computer” and in US patent publication 2003/0193478 to Ng et al., titled: “Reduced Keyboard System that Emulates QWERTY-type Mapping and Typing”, the disclosures of which are incorporated herein by reference in their entirety.
The arrangement of the letters on the keys is an important concern. On the one hand, it is desired to organize the letters on the keys in a manner which maximizes the probability that the system will guess the words intended by the user. On the other hand, it is desired to select an arrangement which will allow users to easily find the key to be actuated for each letter. Two known arrangements of letters are commonly used: the QWERTY arrangement and the telephone keypad arrangement in which the keys are arranged according to the order of the alphabet. US patent publication 2006/0018699 to Rak et al., titled “Keyboard Apparatus”, the disclosure of which is incorporated herein by reference in their entirety, suggests using the QWERTY arrangement.
Another problem of mobile devices is entering symbols other than the alphanumeric characters. The number of keys on the mobile devices is limited and various methods have been suggested to allow simple entering of symbols with limited keys. Still there is a need for better solutions.
US patent publication 2006/0123354 to Volovitz, the disclosure of which is incorporated herein by reference, describes a data entry system in which mode keys are used to change the meaning of other keys of the data entry system.
Chinese patent publication 101286096 describes keys that become mode keys in response to pressing a first mode key.
Some mobile devices receive user input through a touch screen. Touch screens are also used on non-portable devices. US patent application 2007/0097092 to Jung et al., titled: “Method of using a Touch Screen and user interface apparatus employing the same”, the disclosure of which is incorporated herein by reference in its entirety, describes using a touch screen with a plurality of zones having identical keys for different users.
US patent publication 2009/0073002 to Alvarado describes a scheme in which the letters of the alphabet are entered by straight line traces on a touch screen. The touch screen is divided into various cells and traces in different locations are given different interpretations.
US patent publication 2002/0180797 to Backman uses a combined method of strokes and key presses to enter words. The strokes are assigned to the vowels and to shortcuts.
U.S. Pat. No. 7,519,748 to Kuzmin, titled: “Stroke-Based Data Entry Device, System and Method”, describes a method in which strokes are associated with letters for input. The strokes are interpreted according to their direction and their starting zone.
U.S. Pat. No. 7,170,496 to Middleton, describes an input method using gestures of a data entry system. The system provides feedback in the form of the symbol corresponding to the gesture currently entered, so the user can change the gesture if necessary.
These methods require that the user remember the associations between the strokes and the letters, which may be problematic for some users.
Several other input methods may be used with a keyboard having few keys wherein to each of at least some of said keys more than one symbol such as character or letter are ambiguously assigned. In such keypads, generally an interaction such as a pressing action on a key may ambiguously correspond to any of the symbols assigned to the key (such key may be called an “ambiguous key”).
According to one method, a multi-tap scheme in which the user indicates the intended letters by using different numbers of taps on the same key may be used for disambiguation. Use of a multi-tap scheme, however, is slow and inconvenient to many users.
According to another method, in order to enter one of the symbols (such as a letter) among the group of symbols assigned to a key, the user may provide a predefined interaction with the key such as a pressing action on the key and provide a speech information corresponding to the symbol (such as speaking the appellation of the letter) for selecting the letter among the letters that are assigned to the key, and wherein the speech information may be detected and analyzed based on at least one of, the user's voice and/or the user's lip movements. According to one method symbols such as letters having ambiguously resembling predefined speech and that are hard to distinguish from each other through their corresponding speech may be separated from each other being assigned to different keys.
The data entry systems providing precise characters may be combined with the principles of a word predictive system based on key presses alone, to provide a highly accurate data/text entry system using few keys. The principles of word predictive systems based on key presses alone (e.g. T9) are known by people skilled in the art.
Methods for text entry using word predictive systems in which at least one letter is input unambiguously and other letters can be input ambiguously, are known. WO 2009/027817 (to Ghassabian) describes a data entry system that uses a system having two keypads. The first keypad has all the letters of an alphabet distributively assigned to a small number of keys (e.g. four) such that at least two of the letters are assigned to at least one of said keys of the first keypad keys. The second keypad (for example a telephone-type keypad) generally also includes all of the letters of the alphabet of the language, distributively assigned to at least some of its keys such that at least two of the letters are assigned to at least one of the keys of the second keypad set of keys. Typically, the letters are distributed such that an ambiguous key of the first keypad and an ambiguous key of the second keypad have preferably at most one common letter/character. For entering a letter precisely, the user may first press on the key of the first keypad to which said character is ambiguously assigned. The system may predict an undesired character. The user then may press on the key of the second keypad to which the desired character is also ambiguously assigned. As described, said pair of keys may have at most one common character which in this case is the desired character. The system thus provides said the desired character.
For entering a word the user uses/taps-on the corresponding keys of the first keypad and the system predicts a corresponding word (if the word is in the dictionary), or a chain of characters (if the word is not in the dictionary). A correction procedure may be performed by the user when the system offers (predicts) an undesired word, in which the first keypad is used for character entry and the second keypad is used to replace one (or more) ambiguous character of the predicted word by one (or more) precise character (to correct a wrongly predicted set of characters). By using key-presses of two keypads, the data entry system may provide precise character identification, with the unique character common to the two keys being unambiguously selected thereby. By considering the ambiguous characters and the precise character(s) provides as described, the system may propose another word to the user.
Word predictive systems based on key press information use at least a dictionary of words that may also include a database the corresponding key presses for each word.
Data may be input through means other or additional to key presses. For example, a user may perform gliding actions upon a touch sensitive screen to duplicate or imitate key interactions.